The disclosed technology relates to an antiwear agent and lubricating compositions thereof, and an improved method for preparing the antiwear agent. The invention further provides for a method of lubricating a driveline device or a grease application by employing a lubricating composition containing the antiwear agent. The lubricating compositions are also useful in industrial lubrication and metalworking applications.
Driveline power transmitting devices (such as gears or transmissions, especially axle fluids and manual transmission fluids (MTFs)) and grease applications, present highly challenging technological problems and solutions for satisfying the multiple and often conflicting lubricating requirements, while providing durability and cleanliness.
The development of new antiwear chemistry for such applications as gear oils has been driven by the desire to provide chemistries that meet modern lubricating requirements, provide thermo-oxidative stability and cleanliness, and have non-objectionable odor. Many current phosphorus antiwear or extreme pressure additives contain sulfur. Due to increasing environmental concerns, the presence of sulfur in antiwear or extreme pressure additives is becoming less desirable. In addition, many of the sulfur-containing antiwear or extreme pressure additives evolve volatile sulfur species, resulting in lubricating compositions containing antiwear or extreme pressure additives having an odor, which may also be detrimental to the environment or evolve emissions that may be higher than increasingly tighter health and safety legislation specifies.
One development in recent years to address some of these problems is disclosed in PCT Publication WO 2008/094759, Aug. 7, 2008, which reports a lubricating composition of an oil of lubricating viscosity and a sulfur-free amine salt of either (i) a hydroxyl-substituted diester of phosphoric acid, or (ii) a phosphorylated hydroxy-substituted di- or triester of phosphoric acid. In one embodiment, the salt of a hydroxy-substituted diester of phosphoric acid may be prepared by a process comprising (i) reacting a phosphorylating agent with an alcohol, to form a mono- and/or diphosphate ester; reacting the phosphate ester with an alkylene oxide, to form a hydroxy-substituted diester of phosphoric acid; and salting the hydroxy-substituted diester of phosphoric acid with an amine and/or metal.
There is a continuing desire, however, to improve the process for preparing material such as those described in WO 2008/094759. In particular, a process is desired which minimizes the undesirable oligomerization of propylene oxide and leads to higher conversion to desirable products with shorter reaction time.
The disclosed technology, therefore, solves one or more of the above-identified problems by use of the process as described hereinafter.